The evolution of computer screens has been progressively achieving higher resolution, brightness, sharpness, response time and contrast ratio. As screens are becoming larger, brighter and sharper, they are generally easier to read from a greater distance and wider angles. For example, laptops with passive-matrix screens, popular in the late 1990s, have been replaced with active-matrix, or TFT screens, in which each pixel is illuminated. The direct result is that a computer's TFT screen appears clearer and easier to read from a greater distance and wider viewing angle. New technologies continue to improve computer screens by increasing brightness and reducing glare, making screens easier to read in daylight and from greater distances and wider angles.
While the trend of bigger, better, brighter, and sharper screens offers a great benefit to the user, it also presents a drawback: the content of the screen may be more visible to prying eyes in the vicinity of the user. The proliferation of portable computers and their usage at public places, coupled with their larger-and-better-than-ever screens, compromise privacy. For example, more and more corporate users use their portable computers for work of potentially sensitive nature-ordinarily conducted behind closed doors in an office—at public places such as coffee shops and airplanes, where their screens could be read by dozens of people at any given time.
In recognition of the increased need for privacy demanded by computer users, hardware manufacturers have introduced hardware-based monitor security devices. Examples of hardware-based monitor security devices include computer privacy filters, or screens (collectively, privacy filters, unless otherwise noted), introduced by companies such as 3M®, feature a physical device that is adhered to, or placed over, a computer screen. Once such privacy filter is applied (i.e. placed over or adhered to) to a computer screen, its optics are designed to distort the view of the computer screen, when viewed from a wide angle or greater distance. The usage of a privacy filter may keep information displayed away from prying eyes, as a person to either side of the user may find their view of the computer screen distorted and intangible. Other related hardware-based monitor security devices are computer LCD screens that are manufactured in such way that they can be “read” (or viewed in a tangible way) only by a user sitting directly in front of them.
Hardware-based monitor security devices have multiple drawbacks. Among these drawbacks is the bulk and inconvenience, especially for mobile computing. Some filters are not easily removed from a monitor to allow viewing without the distorting effect of the screen, which users may want to do when security is less of a concern (as when a computer user may be using the computer to show something to others). Additionally, hardware monitor security devices in the form of privacy screens are ineffective in giving the audience of a presentation on a large display, such as an LCD projector or large flat screen TV, privacy from prying audience who may be standing a substantial distance away. (e.g. a LCD projected presentation at a company board room with glass walls, where people standing outside the room may be able to see sensitive projected information). There are other limitations and drawbacks of hardware monitor security devices to those described above.